Method for preparing knit fabrics



Oct. 11, 1966 B. G. LESLEY METHOD FOR PREPARING KNIT FABRICS 2Sheets-Sheet 1 Filed May 11, 1962 34500 6'. zfyzfi INVENTOR.

Oct. 11, 1966 B. G. LESLEY 3,277,673

METHOD FOR PREPARING KNIT FABRICS Filed May 11, 1962 2 Sheets-Sheet 2United States Patent 3,277,673 METHOD FOR PREPARING KNIT FABRICS BascumG. Lesley, Pickens, S.C., assignor to Deering Milliken ResearchCorporation, Spartanburg, S.C., a corporation of Delaware Filed May 11,1962, Ser. No. 194,029 4 Claims. (Cl. 66-86) This application is acontinuation-in-part of my application Serial Number 804,418, filedApril 6, 1959 (now abandoned).

This invention relates to novel knitted fabrics and methods for makingthe same and more particularly the invention relates to knit fabricshaving a raised nap or pile surface effect on one face thereof.

It is known that knit fabrics having a pile or nap surface effect can beprepared by knitting a fabric with a large number of relatively longfloats on the reverse side thereof, stretching the fabric lengthwise insuch a manner as to result in slackening of the float yarns, andthereafter brushing the fabric with a stiff brush to result in raisingof the float yarns and to provide a raised nap or pile effect. Because:of the two additional process steps which are necessary for making suchfabrics and because of the care which must be exercised in performingthese additional process steps, such fabrics are inherently quiteexpensive. Further, the originally formed flat lying floats in a knittedfabric have been caused to be raised by scouring the fabric, but sucheffects an uneven wavy raised float surface. In addition, the pileeffect which can be obtained by such processes is quite limited ecausethe loops formed by the float yarns are inherently quite open in natureand only a limited degree of slack can be introduced into the floatyarns as a result of stretching the fabric.

It is an object of this invention to provide knit fabrics having morepronounced pile surface effects than were heretofore available.

It is another object of the invention to provide a simple, inexpensivemethod for producing knit fabrics having pile surface effects.

It is still another object of the invention to provide methods forproducing knit fabrics With a wider variety of pile surface effects thancan be produced by prior art procedures.

According to this invention, a knit fabric having a pile surface effectis produced by a process which includes knitting a two bar fabric fromfirst and second warps, one of the warps being formed of yarns ofrelatively high elasticity (i.e., capable of from about 50% or more moreelastic elongation before breaking) and being knitted under a relativelyhigh tension such that stretched loops are pulled by the needles andsmall tight stitches are formed upon the retraction of the stretchedelastic yarn loops formed of this yarn. The stitches from this highlytensioned warp, in large measure, give the fabric its body and size, andcarry the stress load when the fabric is placed under tension. Thesecond warp is knitted under a relatively low tension and such that thelength of the Warp yarn consumed in knitting the fabric is greater, andpreferably at least about 40-50% or more greater, than would be requiredfor knitting a balanced fabric of any given construction. By the termbalanced fabric is meant a fabric in which the amount of yarn fed to andlying in the fabric is the amount required to equally accommodate all ofthe movements of the yarn guides and needles during fabric formation.'It is the laps of the stitches formed from the loosely tensioned warpthat protrude from the small tight knit foundation of the fabric toproduce a raised nap or pile effect. This pile effect may be accentuatedby setting at a maximum, or

3,277,673 Patented Oct. 11, 1966 increasing, the distance from thesinker throat to the needle head at the bottom of the needle travel, inorder both to increase the length of the loops which are thereby drawnof the loosely tensioned yarn and to pull the preceding tight elasticyarn loops tighter and thereby push the loose loops to a furtherprotruded position relative to the foundation of tight small stitches.

The invention will now be explained in greater detail with reference tothe accompanying drawings in which:

FIGURE 1 is a schematic drawing showing the relative positions of oneneedle position of a conventional bearded needle tricot knitting machineafter the overlap movement of the guides about the needles and theclosing of the beard about the lapped yarn, with the next precedingfabric loops being landed onto the closed beards by the combined motionof the sinker bar and needles.

FIGURES '2 and 3 are further schematic views similar to FIGURE 1, andillustrate the further steps of knockingover or casting off of thepreceding tight elastic yarn loop (FIGURE 2) and the subsequent movementof the needle to the lowermost position thereof beneath the sinkerthroat to pull the loosely tensioned loop to a maximum length and toelastically stretch the highly tensioned elastic loop and also pulltighter the previously tight elastic loop.

FIGURE 4 is a schematic representation of the sinker and needle ofFIGURE 1, illustrating various distances between the needle and sinkerthroat.

FIGURE 5 is a drawing of the back side (normally the face) of a two bartricot knit fabric according to the invention and FIGURE 6 is a drawingof the face of the fabric of FIGURE 5 illustrating the raised lapportions of the stitches formed from the loosely knit warp which resultin a pile effect.

The invention may be practiced with a conventional warp knitting machinehaving two sets of yarn guides 11, 13, mounted on guide bars, not shown,arranged for swinging and lateral endwise movement with respect to acorresponding plurality of needles 15 mounted in a needle bar, notshown, which needles are movable up and down with respect tocorresponding plurality of sinkers 17 which are moved in and out withrespect to the needle 15 during the knitting cycle to effect the landingand knocking over of the loops. The needles may be of the bearded,latch, or tongue type, the instant example being illustrated withrespect to a bearded needle arrangement employing a conventional presser19, which is movable in and out to selectively close and open the beards15a of the needles, as in the conventional knitting cycle of suchmachines.

In knitting a fabric F in accordance with this invention, one warp ofyarn X with a relatively high degree of elasticity is maintained under arelatively high tension, while the yarn Y of the other warp is heldunder relatively low tension, the tension differential beingsubstantially greater than would be necessary to effect a balancedfabric of the two yarns. As a result of the difference intensions, thestretched loop around each needle formed from a warp yarn under hightension tends to snap back and slide off of the needle appreciablybefore a loop around the same needle formed from an end of yarn from thewarp under relatively low tension (see FIGURE 2), for the effectiveretracted length of the highly tensioned yarn forming the other loop foreach needle is substantially less than the distance A between the throatand the head end of the needle at this lowermost position of the needle,wheras the amount of low tensioned warp yarn pulled into the loop duringthe loop forming portion of the needle travel (see FIGURE 3) isapproximately equal to or more closely equal to tract to a substantiallysmaller effective length.

d the distance A between the throat 17a of the sinker and the head b ofthe needle 15, the more highly tensioned elastic yarn being stretched asubstantial amount to accommodate this descent of the needle, while uponupward movement and release of this loop the loop will re- The eifectivestitch length of the stitches 31 formed from the highly tensionedelastic warp yarn X is much less upon retraction than the stitch lengthof the stitches 33 formed of the warp yarns of relatively low tension,due both to the difference in tension and the elasticity of the morehighly tensioned yarns. The length and width dimensions of the fabric Fare determined substantially by the stitches 31 formed from theretracted elastic warp yarns X which have been formed under a relativelyhigh tension and the excess yarn in the stitches 33 formed from the warpY under a relatively low knitting tension accumulates in the joiningloop portions of the stitches and results in these portions of thestitches becoming raised from the surface of the fabric at the time offabric formation. As illustrated in the schematic drawings of FIGURES13, the raised pile or nap surface is formed by the stitches 33 of theyarn Y on the bottom side of the fabric, with the more highly tensionedelastic yarns X being more predominant in the foundation and on theupper side of the fabric.

In order to form the desired effectively small tight stitches 31 withthe relatively elastic and highly tensioned warp yarns X it is desirablethat the knitting ma chine should be set such that the fronts of theneedles 15 are disposed relatively close to the throats 17a of therespective sinkers 17 when the sinkers are in their most forwardposition, i.e., the distance corresponding to that indicated by theletter B in FIGURE 4 of the drawing should be relatively short,dependent upon the number of courses per inch being formed in thefabric, and may be as low as zero distance for a fabric of high coursenumber (e.g., 70-80 courses per inch.) This is desirable in order tobest accommodate the small tight knit stitches 31 formed by the highlytensioned elastic warp yarn as such stitches lie in the fabric and afterretraction of the yarn X therein.

The extent of raised pile effect may be accentuated by adjustment of theneedle height with respect to the sinker throat when the needle is inits lowermost loop forming position. It is desirable to adjust theneedle height such that the heads 15b of the needles 15 are almost evenwith but slightly above the bottoms of the sinkers 17 when the needles15 are in their lowermost position in order to accentuate the pileeffect to a maximum extent for a given tension differential. This servesboth to pull a desirable large length of loop in each of the looselytensioned warp yarns, while stretching the more highly tensioned elasticWarp yarn and thereby pulling more tightly the preceding stitch ofhighly tensioned elastic yarn, both of these results tending to increasethe pile results. If less than the maximum possible raised pile heightobtainable with this setting is desired, it can readily be obtained bydecreasing the tension differential in the two warps. Normally, a pileeffect of suitable intensity for any purpose can be readily achievedwith the needle height adjusted as above described, but if an even moreintense pile effect is desired, such can be obtained by equipping theknitting machine with deeper than normal sinkers and adjusting theneedle height even lower than is possible with conventional sinkers.

It will be understood that the needle height adjustment mentioned aboveis of importance largely because it permits a greater differential inthe knitting tensions of the two warps, and it is the large differencein tensions under which the two warps are knitted and the elasticity ofthe higher tensioned warp yarns that are primarily responsible for thepile effect being obtained. The tension differential that is required ismuch larger than is normally encountered in an improperly adjustedmachine on which an effort is being made to knit a balanced fabric, andfor a fully satisfactory pile effect the tension difference should be atleast 40% greater than would be required for forming a balanced fabricof the same construction, and preferably at least 50% more yarn isconsumed in knitting the loose warp than would normally be used inknitting a balanced fabric of the same construction, although lesstension differential and less excess yarn may be used if desired for alesser degree of raised pile effect. For example, when knitting apattern for a balanced fabric which requires the same amount of yarn forthe front and back warps, such as a 1-0, 12; 12, 10 pattern, the run-inor take-up length for one warp should be at least 40% longer than therun-in length for the other warp. When the stitch pattern for the backwarp is diferent from the stitch pattern for the front warp so thatdifferent amounts of the two warps are normally consumed in knitting abalanced fabric in order to accommodate the difference in warp yarnsrequired for the balanced fabric, the above can readily be employed as aguide to produce a satisfactory fabric by calculating the approximatewarp length ratio necessary to give a balanced fabric of the selectedpattern, if this is not already known, and determining the tensiondifferential necessary to provide a run-in length for one warp at least40% in excess of the approximate length which would normally berequired. For instance, in a fabric with floats formed on one surfaceand requiring perhaps 20% tension differential merely to accommodate theguide bar movements in forming the floats, the tension differentialwould preferably be increased to about 60% or more according to thisinvention, and the normally fiat floats would be raised away from themore tight foundation stitches. There is no upper limit as to thedifference in tensions between the two warps except that dictated by theconsiderations that the tight warp must not be so tightly tensioned withrespect to its stretchability that excessive yarn or needle breaks areencountered and that the slack warp must not be so loosely tensionedthat the needle cannot be drawn free of the loops formed thereform.

In some instances above only two warps have been mentioned, but it willbe understood that a fabric can be knit according to this invention on athree bar machine. In some instances, the third warp can be knit such asto complement either the warp knit under high tension or the warp knitunder relatively low tension, or the third warp can be simply floatedinto the fabric for additional effects. Normally, however, a two barknitting machine is employed in the manufacture of fabrics according tothis invention, for the reasons that only two warps are necessary togive the desired results, and two bar machines generally operate athigher speeds, and for the further reason that two bar machines are morecommonly available.

It is possible to knit fabrics according to this invention with the warpunder a relatively high tension fed to either the back or the front barof a multi-bar knitting machine but it is generally preferred that thewarp under a relatively high tension be fed through the guides 13 of theback bar and that the warp under a relatively low tension be fed throughthe guides 11 of the front bar. This is because as the loops are formedon the knitting needles, the yarns from the back bar guides 13 generallybecome disposed above the yarns fed from the front bar and since it isnecessary for the loops in the yarns under a relatively high tension tobe removed from the needles prior to the time that the loops formed fromthe warp under a relatively low tension are removed, less interferencebetween the two yarns is encountered if the back guide bar is used forthe high tension yarns and the front guide bar is used for the Warpyarns under a relatively low tension.

Almost any type of yarn can be employed as the lightly tensioned warpyarn forming the pile cover in the manufacture of fabrics according tothis invention; however, the tighter tensioned warp must be formed ofrelatively elastic yarn (preferably capable of about 40 or 50% or moreelastic elongation without breaking), continuous filament yarnsgenerally being preferred and giving the most desirable results,although some staple yarns such as worsted yarns having a good elasticrecovery after being stretched about -20% are usable to a degree as themore highly tensioned yarns. Examples of suitable yarns include 15denier, 3 filament nylon, type 66; 40 denier, 13 filament nylon, type 6;70 denier, 34 filament Dacron polyester yarn; and 100 denier, 40filament Orlon acrylic yarn. The total denier of yarns employedaccording to this invention can range from 7 denier, for very sheerfabrics, to several thousand denier, for rugs or the like, and thedenier per filament may range from about 0.8 to 20. Monofilament yarnsalso can be employed and interesting effects can be obtained with suchyarns, particularly where the monofilaments have been processed toimpart a crimped or exaggerated elastic nature thereto.

The knitting pattern employed is of no great importance except that itis generally preferable to employ a pattern for the highly tensionedwarp yarns which would not result in splitting even in the absence ofthe other warp. Excellent pile efiects can be obtained by the use ofknitting patterns such as 1-0, 1-2 for the back warp knitted under hightension, and 1-2, 10 for the front warp knitted under low tension. Ifdesired, however, more complicated patterns, such as float formingpatterns, can be employed, and examples of other suitable patternsinclude: l-O, 1-2 back; 23, 1-0 front: 1(), l-2 back; 3-4, 1-0 front:and 1-0, 1-2 back; 4-5, 1-0 front. Generally, it is desirable that boththe high tension and the low tension warps be full but if area effectsare desired, either one or, in some instances, both warps may bepartial.

Conventional finishing procedures are suitable for fabrics madeaccording to this invention and the usual steps are scouring, dyeing,and heat-setting. If desired, softening agents or other conventionalprocessing agents can be applied. Likewise, if the fabric is knitpartially or entirely from elasticized thermoplastic yarns, the fabriccan be subjected to a conventional operation for intensifying theelastic nature of the yarn, and particularly the highly tensioned warpyarns.

The invention will now be illustrated by the following specificexamples:

Example I A 28 gauge Reiner Tricot machine adjusted such that theneedles pass 60/1000 in. under and 8/1000 in. behind the throats of thesinker, is loaded with two denier, 7 filament nylon, type 66 warps. Thepattern wheel for the front guide bar is set to knit a 2-3, 1-0 stitchand the pattern wheel for the rear guide bar is set to knit a 1-0, l-2stitch. The tension is adjusted such that the back bar runner length is30 inches per rack and the front bar runner length is 75 inches perrack. This results in a fabric of about 3 /2 inches quality that has,when finished, a beautiful suede appearance.

Example II A 28 gauge Reiner Tricot machine adjusted as in the precedingexample is loaded with two 40 denier, 13 filament nylon warps and thepattern wheel for the front 6 guide bar is set to knit 1-0, 4-5, and thepattern warp for the rear guide bar is set to knit 1-2, 1-0. The tensionadjustments are then made such that the runner length for the back warpis 33 inches and the runner length for the front guide bar is 112inches. The resulting fabric has a very noticeable pile effect whichresults in a very desirable appearance and feel.

Having thus described my invention, what I desire to claim and secure byLetters Patent is:

1. The method of forming a raised pile surface knitting fabric with aknitting machine having two guide bars and a needle bar, comprisingforming two loops from two yarns on each of a plurality of needles onsaid needle bar, one of said two yarns on each said needle being capableof substantial elastic elongation, stretching one loop formed of saidone elastic yarn during loop formation on each of a plurality of needleswhile effecting substantially less stretch on the other said loop duringloop formation, and permitting retraction of said substantiallystretched loop after casting oif thereof to thereby form a raised pilesurface of said other loops, with the stretched and retracted yarn loopsbinding said other loops in place, and permitting the stretching duringformation of each succeeding stretched loop to pull the precedingretracted said one loop tighter to thereby force the preceding adjacentsaid other loop further away from the foundation plane of the fabric asformed by said retracted loop.

2. The method according to claim 1 including maintaining the inputtension of said one elastic yarn forming said one loop substantiallyabove that of the yarn forming other said loop and substantially abovethe tension required for a balanced fabric construction.

3. The method according to claim 1 including permitting the feed of theother said yarn to form a loop thereof of a first size upon thecompletion of the loop-pulling portion of the needle stroke, Whilepermitting the feed of said one elastic yarn to form a stretched loopthereof of size substantially equal to said first loop size but ofsubstantially smaller effective loop size than said first loop size uponpermissive retraction thereof after casting off.

4. The method of forming a knitted fabric having a raised nap surface,comprising successively pulling two yarns into loops on each of aplurality of needles and casting off said loops to form a knittedfabric, one of said yarns being elastically stretchable and beingsubstantially stretched during loop formation while the other of saidyarns is at a comparatively light tension and comparatively unstretchedduring loop formation, whereby the effective retracted length of suchsaid one loop, after casting off, is substantially smaller than theeffective length of each said other loop, to thereby yield an elasticfoundation knit fabric having a raised nap surface formed of said otherloops.

References Cited by the Examiner UNITED STATES PATENTS 1,475,325 11/1923Springthorpe 66191 2,114,004 4/ 1938 Reinthal 66195 2,220,428 11/ 1940Shager 66-194 2,267,578 12/ 1941 Schonfeld 66-86 2,435,897 2/ 1948Newman 66-193 2,757,529 8/ 1956 Moore 66194 3,063,272 1 1/ 1962 Bolton6686 FOREIGN PATENTS 226,299 12/1924 Great Britain.

MERVIN STEIN, Primary Examiner.

RUSSELL C. MADER, DONALD W. PARKER, J. H.

LACI-IEEN, P. C. PAW, Assistant Examiners,

1. THE METHOD OF FORMING A RAISED PILE SURFACE KNITTING FABRIC WITH AKNITTING MACHINE HAVING TWO GUIDE BARS AND A NEEDLE BAR, COMPRISINGFORMING TWO LOOPS FROM TWO YARNS ON EACH OF A PLURALITY OF NEEDLES ONSAID NEEDLE BAR, ONE OF SAID TWO YARSN ON EACH SAID NEEDLE BEING CAPABLEOF SUBSTANTIAL ELASTIC ELONGATION, STRETCHING ONE LOOP FORMED OF SAIDONE ELASTIC YARN DURING LOOP FORMATION ON EACH OF A PLURALITY OF NEEDLESWHILE EFFECTING SUBSTANTIALLY LESS STRETCH ON THE OTHER SAID LOOP DURINGLOOP FORMATION, AND PERMITTING RETRACTION OF SAID SUBSTANTIALLYSTRETCHED LOOP AFTER CASTING OFF THEREOF TO THEREBY FORM A RAISED PILESURFACE OF SAID OTHER LOOPS WITH THE STRETCHES AND RETRACTED YARN LOOPSBINDING SAID OTHER LOOPS IN PLACE, AND PERMITTING THE STRETCHING DURINGFORMATION OF EACH SUCCEEDING STRETCHED LOOP TO PULL THE PRECEDINGRETRACTED SAID ONE LOOP TIGHTER TO THEREBY FORCE THE PRECEDING ADJACENTSAID OTHER LOOP FURTHER AWAY FROM THE FOUNDATION PLANE OF THE FABRIC ASFORMED BY SAID RETRACTED LOOP.